Line-drop compensator.



V J "PEARSON. LINE DBOP GOMPENSATOR. APPLICATION FILED 001-. 10, 1901.

Patented Jan. 7, 1913.

3 SHEETS-SHEET 1.

Tgafghif.

UNITED srarrs ornron JOHN PEARSON, or. SOMERSET; WISCONSIN, ASSIGNOB OFONE-'THIBD'TOIAHES' E;

WILLIAMSON Ann olvn-six'rn 'ro FRANK. I). MERCHANT, or MINNEARQIJmIMmNE;

sore. mnnmaor COMPENSATOR.

1,050,0 1; Specification of Letters Patent. I Pat te J ,,7,1913;

Application fil ed October 10, 1907; Serial No..396,808l

T all whom it may concern:

Be it. known that I,'JoHN-"PnARsoN, a citizen of the United States,residing at Somerset, in the county of St. CroiX and Statecf Wisconsin,have invented certain new and useful Improvements in Line-DropCompensators; and Ido hereby declare the following to, be a'full, clear,and exact description ofthe invention, such as will enable othersskilled in the art to which it appertains to make and use the same.

My invention has for its object to provide .an eitici'ent compensatingmeans for regu lating an alternating current generator so as tomaint-ainconstancy of voltage, was nearly so as possible, at thedistributing end of along distance transmission line; and

to this end, my invention consists of the novel means for this purposehereinafter disclosed and pointed out in the claims.

The desirability of keeping the voltage constant, or as nearly constant.as possible, at the distributing end of an alternating currenttransmission line has long been well recognized. In practice, however,this has been found to be an extremely difiicult problem. If thetransmission line is supplytween current and voltage, onthe line, are

greatly increased, as compared with some other-classes of service. If,for example, the line is supplying simply an-incandescent lightingsystem, as is common in night service, the power factor will becomparatively highibu't if supplying motors, especially induction motorsas is common in day service, the poWer-factor'will be comparatively low.The self-inductance, the capacity of the line, and the ohmic drop orresistance of the line, must also be taken into consideration. Becauseof all these things taken collectively, practice shows that there is atendency for. a transmission line to decrease the voltage at thedistributing end if the current lags behind the voltage; and to increasethe voltage at said distributing end, if the current leads the voltage.The drop in the voltage inci'den'tal to-thelag of thecurrent and ohmicresistance of the line has been most' generally considered, and isgenerally spoken of as. line drop. So far as I know, no successful meanshave ever been provided, in the prior art, for the complete compensationof these voltage variations at the dismission line sup lied through awhich is of solenoid form and has two coils,-

one for voltage and the other for current, with circuit connections fromthe main line, and which elements are designed to compensate for I R-losses; or, more loosely stated, they. are intended to compensate forlosses due to current and resistance; Thesaid Tirrill regulator doesthus take more or less note of variationsin load,;but it does"- not takesufiicient note of power factor changes. The standard Tirrill regulator'will compensate, fairly well, when the, power factor does notvarymuchybut, in'cases where the power" factor varies from to percent.the-voltage will vary several percent. at the distributing end of "atransgenerator controlled by a irrill regulator.

I am also aware of the so-called Mers'hoii"v compensator; but where aninductive resistance and ohmic resistance are conn'ectdinparallel, as inthe Mershon compensator,

there will be a tendency to increase or decrease the voltage, wheneverthe frequency changes;- for the reason that, when the fre-.

quency gets higher, more current will pass through the ohmic resistanceand less through. the inductive resistance. For this reason, the Mershoncompensator cannot, in

'myjudgr'nent, be successfully applied to .'a

Tirrill regulator,- nor to a compound wound exciterg but might possiblybe applied to a reading instrument, such, as a' voltmeter, wherein verylittle current only is needed.

My new compensating means, herein-dis closed, is intended not onlyto.considerthe PR losses, as in the devices of the prior art, but totakefull note of power factor changes. To this end, I provide means fortaking oif current and voltage from the transmission lineand deliveringthe same at a phase difference increased as compared with the phasedifierence on the line, so as to thereby secure a resultant which willbe effective for effecting the required compensation, when applied, forexample, to the alternating current control magnet of the Tirrillregulator or to third coil on a compound exciter. The said resultant, sosecured, may be applied simply to a voltmeter, at the generat mgstation, to indicate the voltage at therefer to like parts throughouttheseveral 15 views; Figure 1 is a diagram view illus trating my inventionas applied to the Tirrill regulator. Fig. 2 is a similar viewillustrating my invention as applied to a compound exciter; Fig. 3 is asimilar View illustratingla modification as applied simply to avoltmeter and, Fig. 4 1s a phase diagram.

Referring to Fig. 1,'A represents a three phase generator, and A A and Athe corresponding wires of a long distance transmission line- The fieldof said generator A is subject to an outside exciter The, exoiter B issubject to a voltage regulator C.' This regulator G is so nearlyidentical with the structure of the standard Tirrill regulator that itis suiticient to note the only material difference. S This diflerence isdue to the modification made to adapt, the Tirrill regulator to mycompensating means, as illustrated in Fig. 1; andto this end, theso-called alternating current control magnet of the regulator C employsonly a. potential coil C instead of having the customary pair of coils,andthe resultant from my compensator is delivered to th1s poten tialcoil C of said regulator C. C is the direct current control magnet ofthe Tirrill' regulator. v

The primary. feature of my compensator is what lcall a phasetransformer,.but pref erably also includesa compensating transformer.These devices, with their proper circuit connections, will now bedescribed in detail. The compensatingv transformer K, shown in Figs. 1and 2, has a par of coils K and K one for current and 'the other forvoltage so connected t-hat'the current travels in opposite directionsthere-' through, and between the two is placed a third coil K" whichdelivers the resultant over the wires 8 and 9 tosaidpotential: coil 0 ofsaid regulator C. .As shown. in Figs. 1 and 2, the coil K is a potentialor voltage coil, being connected across the main line by, voltagetransformer H, and the wires 4 and. 5 leadin therefrom to the said coilK and is terefore adapted to take from the:main line a true proportionof the voltage, in step with the voltage on the mainline and of acertain phase rela-..

will tion to the current on the main line. As shown in said Figs. 1 and2, the other coil K? is a current coil. connect ed up with the.

main line, through series transformers D and my phase transformer,which, as shown in Fig. 1, is made up of the parts marked E, E, F and G.The part E is a coil wound on an annular laminated core E and this coilE is tapped at three equidistant-points by the three wires or phaseleads 1, 2 and 3 leading from said series transformerseD.

"These wires 1, 2 and 3 deliver to said coil E current which holds atrue proportion to oted a sectional contact lever G, the outer or endsections of which are insulated from the central section thereof andmaybe made to engage with any desired pair or opposlte members of said tapsF, by swinging the total main line current, on all the phases, and whichis of a certain phase rela- The parts said lever on its pivotal center.The' saidouter ends of said contact lever Ghave off leading wiresmarked, respectively, 6 and 7. The said device, composed of the-saidparts E, E F'and G, is a'dapted'to take from the main transmission linemulti-phase current'or voltage and deliver the same in a single phaseover the wires 6 and 7. With thefcircuit connections as shown, it takesin multi-phase current and delivers the same in a single phase. Thewires 6 and 7 connect with the coil K or current coil of saidtransformer K, the wire 6' connecting directly therewith, and the wire 7through a switch button F -and anyselected one ofa' series of leads Fbrought out from differentpoints along the coil K 7 The purpose of theseries of leads F is to vary the strength of the coil K as may berequired, depending 'on the amount of ohmic drop in thetransmissionline. By changing the contact lever G' from one setor-opposite pair of taps F to anotherv opposite pair of said I taps, thephase of the current taken off over the wires 6 and 7 and delivered tothe coil K relative to the voltage delivered over the other circuit tothe coil K can be changed so as to increase this phasedifference-relative to the phase difi'erence on the main line,

so as to t a resultant in the coil K which will be efictive forcompensation; or which consider. effectively power 'factor changes onthemain Line. Assuming that the said contact lever;"G has beenproperly Iset to thus secure in'the coil K a single phase current of the properphase difference relative to the current in the coil K, for dueconsideration of the power factor changes on the main line, and theswitch button 7 has been connected the'proper member of Wires 8 and 9 aresultant to the potential.-

coil C of'the regulator- C,.\vhich will be effective to secure thedesired full compenm sat-ion. At no load, the E. El. F. in the coils Kand K will-be approximately equal, but as the load-comes on, the currentin coil K begins to reduce the E. ill. F. in the re- 'sultant coil Kjust as the transmission line reduces the E. H. F. at the distributinend thereof; and. this will allow the core of the alternatingcurrentcontrol magnet of the regulator U to drop, with the result thatthe bus bar' voltage Of'l'll generatorwill be raised under the controlof said regulator.

lVhen theload falls oil. the reverse actions, of course, take place.

In all cases. in the coil K sl iifted'in phase more than 3'5 180 de reesin the direction that the main .ci:irrcni; shifts when the mainlinecurrent leads, or example, the required shift may be 60 degrees more,in'order to make the proper compensation for the powerfacton so changeson the main line as shown in the phase diagram Fig. 4: of the drawings.In this phase diagraimthe curve T represents the phase of the current inthe coil. Kt or the one responding to voltage, and the curve Trepresents the'phase of the current in the coil 1& or the one respondingto cur-- rent. on power factor unity. By reference to this diagram, itwill be seen that the phase of thccurrent in coil, K is sixty elec- 4etrical time degrees ahead of the phase hf the current in the coil K andthat the two are in opposition to a certain extent. This sixtydeg'reesof difference on. power factor I unit-y is-due to the positionat which the st'alever G of the phase transformer is set; and it isbecause of this increase of the said phase difference that the resultantin the coil K is rendered effective. Having thus shown the phasedisplacement on unity power factor, it can readily be seen that as themain line current lags, thecurrent in coil K will also lag and come morenearlv in opposition to the current in the coil K thereby reducing thestrength, of the resultant coil K the resultant coil K These 'areprecisely the actions required to secure compen- Rdesiredg. Thequestmhfthen arises nit be: known which is the proper tocction-to.swingthe contact lever G. The er, is that the phasetransformer1s s desirable to have currenttestcd outand graduated for that purpose,for the particular line where applied. That this can be readily done,may be understood from the following statements. The field of the core Eis rotating. Let it be assumed 7 that this field rotates. counterclockwise; that the phase transformer is connected as shown in Fig. 1,and that the power factor of the line is, at a given instant, 1.00 percent. 'Then swing the lever G one way or the other, until the core, ofthe alternating". current control magnet of the'reogulator C drops toits lowest point, and mark the position at which the said-lever G stoodon the core E This. for example, may. be the g dotted line position of.said lever, as shown in Fig. l. At this, which might be called the firstposition for the purpose of graduation. the current in the coils "K andR will be in opposite phase, inasmuch as the power factor is 100 percent. Next, take a reading of the power factor of the-system when thecurrent lags about 30 degrees, and

shift the lever G again, one way or the other,

until the alternating current magnet core of the regulator C again dropsto its lowest point. and mark the then positionof said lever on the coreE. This may be called the second graduating DOSltlOlL- Finally, take areading of the power factor of the systemwhen the current leads, about,30 degrees, and then shift the lever G again, one way or the other,until the core of thee alternating current control magnet again drops toits lowest point and mark the position of said lever G on thecore EhThis may be called the third position for graduating" purposes.Thereafter, by referring; to these three graduation marks on the core Ethe operator will know, by the position of the contact lever G, when thecurrent in the coil It? is in opposite phase relative to the current incoil K on power factor 100 per cent; and will further know in whichdirection from this primary graduation the lever G must move for lap; orlead of the current in the coil K relative to current incoil H dottedline position is the one which said lever G would occupy, in my workingsystem, in order to get the current in 'coils K and K in opposite phase,on power factor l00 per cent.

The lever G being adjustable, the samemay be set for any displacement ofphase required to secure complete compensation I it'is not deemednecessary to traceth'e 'andthereby' the desired constancy of voltageatthedistributing end of the line." Some systems require and will standaig'reat'er The compensator, shown 'i'n..Fi'g. 2,-is1identical withthatxshownin ig'. 1, with the'ex-i ception that the core-EP-Jis how'-provided 'With ,twowindings E and. E the former bei'ng connected-to theleads A A A as in Fig. 1, and the'latter hein in inductiverelation tothe said winding sothat the two win-dings E and E, are relatedas primaryand; secondary respectively, and the onlydifierence in thea-ction istha't therebya distinct ind'ucedcurrent is- ,afi'ordedior the" coil Kinstead of current taken-incredirectlyi' from-the main line. Insaid'Fig. 2, Z- represents the generator, ,the fieldof which is subject.to a compound e'X'citenV; and this exciter Vis regulated by mycompensato'r, through-the so-called rectifier R. k The standardconnections from such a compound exciter ,V,.and a rectifier R are Wellknown,

same in detail. It. is deemed sufiicien-t to note the'additions forconnecting in my compensator.- To this end, the compound exciter hasathird winding W, in addition" to the old or series Winding'Y andthe-shunt Winding. X; and which newwinding W etsits '-ci'1rrent, throughthe rectifier R, roin the res'ul'tant'coil Kfof my ,coinpen s ating"transformer K. They course of .the

current is over the Wires Sand. 9, brushes 10,"

slipiringszll' and 12 of the rectifier, thence through the leads 13 andll, to the commuta-' tor 15, and thence over the wires 16 and 17 to saidcoil of the eXciter-V. The wind-'- 'ings X, Y and W, of said compoundexciter,v are all Wound in' 'the same direction on a common core; .andconsequently each winding ishe'lping theother'to raise or lower the V01tage of the exoiter'; and h'ence, of the alternatorandtransmission-line.- With these connections, therefore, the-coil \Vwill cooperate With the 'coilsiX' ancPY of said' compoun exciter, so as'to efiiect compensation .for the voltage changes at: the 'distributmgend of the transmission' line, to thesame effect as the. resultant fromthe compensator acts through the Tirrill regulator in Fig. 1, assumingthat the speed of the generator'Z s constant. Otherwise stated, when the-co1l V is add'edto the' said compound excit er and'connected up withthe other parts-otmy compensator through the. rectifier, the saidcompound excitcr' becomes a w'oltage regulator for the generator Z and1s prop-. erly compensated'as described.

Referring to Fig. 3,, a modification is 1 there illustrated,wherein theconnections ires 6 and L 1s substituted for cooperation with the ant'n'ularcore Bend the coil E .the'reon.. "1fhe v 1; core L,=with 1ts coilM, may he swung so as to span any desired diameter of thecore E, just ascould the contact; 'lever' Ga in the other ..view.' The Wires 1f2and-'3'. are, in Fi 3, connectedga'cross the main line to, 5

fv'o tage transformers H? instead of to series I transtormers, as in theother' v ews; and

the wires sand 5 are now connected with. the main line through a seriestransformer 1 2 e d f acro s the -,ma1n line through voltagetran'sformer's,-a'si-n Figs." l and -2. \Vith this" cons truction, thewinding 11 on the; pivoted core L delivers current over the. 7' topointsof junction with the wires land 5, and thence the resultant, is takenover the wires 8- and -9' tothe taps S of the voltmeter N. It will thusbe seen that the voltmeter N, the secondary o'f-transformer'D and thecoil M are in parallel, so

that the-effective volt-age passing through 109 the voltmeter N will bethe resultant of the voltages from the transformer D and the coil M. .'Inthis modificatiomafl true propor 'tion' of the voltageiwill" be takenfrom all. j the phase leads of the transmission line, and

.be transformed and delivered by the a phase transformer in 'a-singlephase volta over the Wires 6 and .7, and the phase di ere'nce' ofthis'volta-ge relative-to t ecu-rrent sup 'pl ied' over the-gwires [-tand 5 will be in [-110 creased, relative to the base-difference ofthe-main.line,..a nd may varied, by shi ft. ing the position of saidcore L, so .as. to get a resultant from said. two circuits: which willbe eflectiv e whndelivered through tria wires 8 and 9, either for thepllrposes of compensation or for indicating the voltage at thedistributing end of the transmission line. If connected "to "thevoltmeter, as s'hown,'the rading'isfgivelr; but the wires 1 S and 9could be run-to the potential coil C of the Tirrill regulator,'-as shownin Fig. 1, and be used" for regulating purposes.

It will be understood, of course, that it is a great advantage-to know,at the generating station, what 'the voltage is at the distrihutingstation. The deviceconnectcd up as shown ,1 Fig. 3 W111 give thisreading.

was connected to 'take the resultant from the 0011 K as there shown.

It should be further noted, that the com- I pensating transformer K,shown iii-Figs. 1

and 2, coul d be dispensed with, and the two pairs of wires (4 and 5)and (6 and/7) be applied, respectively, tothe pair of oppositely woundcoils of the A. C..control magnet of the standard Tirrill regulator; andtheresultant, from the. sald two circuits from the main line, would thentake effect on the core of that magnet and give thecompensat1onrequired. It is an advantage,

however, to have the compensating trans, former K; because, otherwisethe coils of a be located in the. circuit which takes voltage from themain line.

What I claim is:

1. A compensator having two circuits from niulti-phase transmissionline, one for voltage and the other for current, and having in thecurrent circuit a phase transformer taking a. true proportion of thecur-- rent of the main line and delivering the same in a single phase,of a phase difference,

relative to the current of the other circuit, n'creased as compared withthe phase difference on the, main line. substantially as described.

2. A compensator having two circuits from a multiphase transmissionline, one

- for volt-age and the other for current, and

having-in said current circuit a phase trans former taking a trueproportionof the current of the mainline and delivering the same in asinglephase, of aphase difference, relative to the current of the othercircuit increased to any desired extent, as compared with the phasedifference *on the main line, substantially as described. a coil in eachof said circuits supplied with current by the circuit to which it isconnected, which coils are arranged to act magnetically in opposition toeach other, means for adjusting the strength of one coil with respect tothe strength of the other, and means for utilizing the resultingmagnet-ism to operate a regulating device.

8; A compensator having two circuits from a multi-phase main line, onefor voltage and. the other for current. a phase transformed in saidcurrent circuit taking a true proportion of the current from the mainline'in all. its phases and delivering the same in a single phase, of aphase difference,

relative to' the current of the other circuit,

increased flS-COHIPQI'QCl with the phase difference. on the main line,said phase transformer being adjustable to cause the current to leadorlag to the necessary extent, and means for rendering'the resultant ofsaid two circuits available for indicating or regu; lating purposes,substantially as described.

i. A compensator having two circuits from a inulti-phase main line, onefor voltage and the other for current, a phase transformer in one ofsaid circuits taking a true proportion .of the current from the. mainline in all its phases and delivering the same in a .dering theresultantof said two circuits available for operative purposes, substantially as described.

5. The combination with a multi-phase generator, a transmission line anda voltage regulator for said generator,'of two circuits from thetransmission line, onefor voltage and the other for current, one ofwhich circuits includes a phase transformer taking a true proportion ofthe current or the voltage from the main line, in all its phases, and delivering the same in a single phase, of a difference, relative to thecurrent or voltage from the other circuit increased asconipared with thephase difference on the mainline, means for .adjusting said phasetransformer to cause the current to lead or lag to the necessary extent,anda compensating transformer having two coils fed from said twocircuits respectively, and having also a third coil delivering theresultant of theothe'r two coils to the voltage regulator of saidgenerator, substantially'as described.

6. The combination with a multi-phase generator and transmission line,and 21 voltage regulator for said' generator, of'two circuits from thetransmission line,one for volt age and the other for current, one ofwhich circuits includes a phase transformertaking a true proportion ofthecurrent from the main line in all its phases, and delivering the samein'a single phase, of a difference,

member of which two coils has a series of leads through any selected oneof which theline connections can be made, and which compensatingtransformer has also a third coil delivering the resultant of said twocoils to the voltage regulator of said generator, substantially as andfor the purposes setforth.

.7. A compensator. for multiphase trans m ssion systems,-' comprisingtwo clrcuits from the 'main transmission line one for .voltaige andtheother for c'urrent,a phase transformer in said current circuit, saidphase transformer ncluding an annular core, a coil thereon, and a rotaryadjustable member within theannular core, and means forrendering theresultant of-said two circuits available for operative purposes; I

, 8. A compensator for multiphase transmission-systems, comprising twocircuits" from the main transmission line one for voltage'and the otherfor current-,a phase transformer 1 in one of "said circuits, said.

phase transformer o including an 'annular core, a coil-thereon, and. arotary adjustable -meinberwithin the annular core, and a compensat-ingtransformer having two oppo-' sitely Wound coils'fed from -saidtwocircuits,

respectively, and a :third coil'delivering the resultant, of said twocoils for regulating effects.

9. The combination with a multiphase generator 'and'tran'smission lineand a .voltage regulat r for said generator, of two compensating.-.zircuits from the main tIfiIlS-u mission line, one for Volta I I for current,-a phase transformer n' one of and the other said-circuits, said phasetransformer including an annular core, a coil'thereon'and a rotaryadjust-able member Within theannular core, and a'compensatlng.transformer halv ing two; oppositely Wound coils fed from.saidtwo'circuits respectively, and a third rent, a phase transformer inthe currentcir-' cuit, said. phase transformer including an annular'corehavlng a coil thereon, a ser es of co-nductlng-tapson sa1 d co1l-,arotary ad juistable conductor, arm cooperating with said taps and havingleads extending there; from, and a compensating transformer having twooppositely wound coils, one fed fromthe' voltage circuit'and the otherfrom the rotary conductor arm of the voltage transformer, and a third.coil delivering. the

resultant "of said two coils to theyoltage regulator of the generator.

' In testimony whereof I affix mysignatur e in presence oft-W0.witnesses.

JOHN PEARSON.

ltvitnesses M. Roma's,- H. D. KIL'G'ORE.

